This invention relates to controlled delivery systems targeted to polysaccharide molecules on cell surfaces.
A targeted drug delivery system is most often a drug associated with a macromolecule or particulate carrier, designed to be localized at a specific anatomic region in the target site. Recently, there has been a greater focus on utilizing receptor-mediated carriers, such as monoclonal antibodies, that interact with cell surface receptors at the drug's intended site of action.
An apparent limitation of this type of system is that, following intravascular administration, a large fraction of the carrier may never reach an extravascularly located target site due to the systemic distribution via the blood circulation. There is nothing inherent in the design of these drug carrier systems that will enable the carrier to be localized in the capillaries of the target site.
An alternate approach is to utilize carriers that have receptors on the capillary endothelial cells. This idea has been recently expressed by Ausprunk and Borchardt, Am. J. Pathol. 103,353-366 (1981), with respect to targeting drugs to the brain. They suggest the use of carriers that could be transported across the blood-brain barrier by specialized transport processes (i.e., amino acids), or by receptor-mediated transcytosis (i.e., as suggested for insulin).
It is therefore an object of the present invention to provide a receptor-mediated carrier system for the directed, controlled delivery of biologically active compounds to specific types of cells, such as brain cells.
It is a further object of the present invention to provide a method for making a receptor-mediated carrier system for the controlled delivery of compounds which is relatively easy, uses safe materials, and economically feasible.
It is a still further object of the present invention to provide a receptor-mediated carrier system for the directed, controlled delivery of biologically active compounds to specific types of cells which is flexible but relatively specific.